I have funny story of being helped in a Microsoft store.
I once bought a BLU Windows Phone in a Microsoft store. I really liked having a Windows Phone mostly because no one I ever met had seen one before and both Apple and Android users were shocked when they saw it. :)
After a few years my phone's battery indicator started failing, or at least that's what I think the problem was. The phone would suddenly say it was almost out of battery and had to shut down. When I restarted it the battery indicator would say some more reasonable number, consistent with how long ago I had charged the phone; but after a little while, long before it should have been running out of battery, it would again say it had almost no battery left and turn itself off.
I thought the phone's problem wasn't too serious yet and with some vigilance (checking it frequently to turn it on as soon as it turned itself off) I could use it a little longer. But my wife thought it was time for me to get a new phone, so I went to a Microsoft store only to discover they didn't sell them anymore. I think by then everyone had decided to give up on Windows Phones; I still valued what was their main selling point for me, the shock value, and would have gladly bought another!
At the store I started chatting a bit about my phone with the clerk who told me they didn't sell Windows Phones anymore, a heavyset young man. At some point I wanted to show him something on the phone so I took it out of my pocket but fumbled and dropped the phone. When the clerk saw I was about to drop the phone near him, he lifted the leg nearest the phone, but lost his balance and brought his foot down hard, right on my phone!
After that the phone wouldn't turn on anymore. The clerk was very apologetic and seemed willing to pay at least partially to replace my phone but I insisted that I was about to replace it anyway. I went somewhere else and bought myself a cheap Android phone. My wife was very happy the clerk had stepped on my Windows Phone since I had the left the house unconvinced it needed immediate replacement.
>After a few years my phone's battery indicator started failing, or at least that's what I think the problem was.
You describe the classic symptoms of a failing battery. The charging efficiency of a battery at the end of its life drops through the floor. This confuses the columb counter in the charge indicator: it sees an amp hour go into the battery, but most of it becomes heat, and maybe ten percent is useful charge. Therefore, the battery indicator happily says the battery is at 90% right up to when it abruptly dies.
No, my phone's battery indicator reported a much lower number than what I knew to be true. Say I fully charged the battery and turned on the phone. The indicator would start at 100% and go slowly down as I expected. Then at some point, around 70% the indicator would suddenly jump down to a much lower number, say 30%. If I kept using the phone the indicator would slowly go down at the expected rate, until at some point it would suddenly jump down to like 4%. The phone would then warn me it has extremely low battery and turn itself off.
Now, at this point I could estimate what the true remaining percentage was, just based on how long I had been using the phone. If often turned itself off when I reckoned it should be at 60%. If I turned the phone on again without charging it at all, the battery indicator would tell me that it did indeed have around the 60% charge I estimated.
The battery seemed to be holding charge just fine. If I added up all the usage I got out of a single charge, that time seemed to be about the same as before (a little over a day), it was just interrupted by several rounds of the phone thinking it had no battery left, turning itself on, me turning it on again and the phone sheepishly recognizing then it actually did have a lot of charge left.
Sorry if I didn't explain this understandably in the original comment.
This is great for the powered device, since it's nice and flat, but annoying for determining state of charge from terminal voltage, since it's awful and flat. I have not personally developed a state-of-charge indicator, but I would guess that one might use columb counting for the first half of the curve, then voltage monitoring for the second half, introducing odd discontinuities in the 80%-30% range. A truly clapped out battery will up and die before it got to the second half; a merely old battery will just be strange and inconsistent.
>If I turned the phone on again without charging it at all, the battery indicator would tell me that it did indeed have around the 60% charge I estimated.
Combine these factors, we discover that while your phone was behaving very unintuitively, it might not have been lying. If you hit an old cell phone with a big enough draw, (prime95, bitcoin mining, opening a cnn.com story without adblock) the battery indicator could correctly say that only 4% of the battery is left. Shut it off, letting the battery recover a bit, then turn it back on, and ta dah, by the voltage curve with a light idle discharge, it's got 60% left.
Cell phone batteries generally last two or three years. Four years+ requires light discharges and not recharging it fully. Essentially, not using it at all.
Interesting! I thought the battery itself wasn't the problem mainly because the battery life hadn't gone down (I was still getting the same number of hours between charges if you added up the time my phone was on), but I also didn't know the symptoms I did see were consistent with battery problems. Thanks!
I once bought a BLU Windows Phone in a Microsoft store. I really liked having a Windows Phone mostly because no one I ever met had seen one before and both Apple and Android users were shocked when they saw it. :)
After a few years my phone's battery indicator started failing, or at least that's what I think the problem was. The phone would suddenly say it was almost out of battery and had to shut down. When I restarted it the battery indicator would say some more reasonable number, consistent with how long ago I had charged the phone; but after a little while, long before it should have been running out of battery, it would again say it had almost no battery left and turn itself off.
I thought the phone's problem wasn't too serious yet and with some vigilance (checking it frequently to turn it on as soon as it turned itself off) I could use it a little longer. But my wife thought it was time for me to get a new phone, so I went to a Microsoft store only to discover they didn't sell them anymore. I think by then everyone had decided to give up on Windows Phones; I still valued what was their main selling point for me, the shock value, and would have gladly bought another!
At the store I started chatting a bit about my phone with the clerk who told me they didn't sell Windows Phones anymore, a heavyset young man. At some point I wanted to show him something on the phone so I took it out of my pocket but fumbled and dropped the phone. When the clerk saw I was about to drop the phone near him, he lifted the leg nearest the phone, but lost his balance and brought his foot down hard, right on my phone!
After that the phone wouldn't turn on anymore. The clerk was very apologetic and seemed willing to pay at least partially to replace my phone but I insisted that I was about to replace it anyway. I went somewhere else and bought myself a cheap Android phone. My wife was very happy the clerk had stepped on my Windows Phone since I had the left the house unconvinced it needed immediate replacement.